This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-089738, filed Mar. 28, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a deposition apparatus for coating a substrate to be processed with liquid and, more particularly, to a deposition apparatus used for controlling the amount of coating.
A spin coating method used in a lithography process is known as a method of forming a liquid film on a substrate. The spin coating method has recently been applied to the formation of an insulation film and a metal film. In this method, however, most of chemicals supplied onto a substrate are discharged therefrom and the remaining only several percent chemicals are used for the formation. The chemicals are wasted and adversely affect the environment. Using a square substrate or a 12-inch-or-more circular substrate, turbulent air occurs on the outer region of the substrate to make the thickness of this region nonuniform.
As an apparatus for uniformly coating the entire surface of a substrate with chemicals without wasting them, Jpn. Pat. Appln. KOKAI Publication No. 2-220428 discloses an apparatus for forming a uniform film by discharging a resist solution from a number of nozzles arranged in a line and spraying gas or chemicals onto the film-forming surface of a substrate from behind the resist solution. Jpn. Pat. Appln. KOKAI Publication No. 6-151295 teaches an apparatus for forming a uniform film by spraying a resist solution on a substrate from a number of spray nozzles provided in a rod. In these prior art apparatuses, a uniform film is formed by scanning the surface of a substrate with a plurality of discharge or spray nozzles arranged in a lateral direction. However, the apparatuses cannot locally control the thickness of a film-forming surface of the substrate.
A method of forming a liquid film by supplying chemicals from a nozzle to a film-forming surface of a substrate to be processed is proposed as one for controlling the amount of coating within the surface of a substrate without wasting chemicals. The control of the amount of coating is performed using a precise coating nozzle that can start and stop the discharge of chemicals. The precise coating nozzle controls the amount of discharge by driving a valve of a needle or a screw provided at the upper portion thereof.
The above method has the following problem: When the valve is driven, friction between the valve and the chemicals causes particles, and the particles, which are contained in the chemicals dropped when the valve is opened, are transferred onto the substrate. Immediately after the valve is opened, the pressure exerted on the chemicals varies to produce a pulsating flow and cause a difference in the thickness of a formed film.
As a method of controlling the amount of discharge of chemicals to inhibit the mixture of particles and the production of a pulsating flow, U.S. patent application Ser. No. 09/335,508 discloses a method of cutting off the supply of chemicals by spraying gas on the dropped chemicals from the sides of the chemicals.
In the U.S. Patent Application, a gas generating film is irradiated with light to generate gas, and the pressure of the gas changes an orbit of chemicals discharged from a nozzle. The chemicals whose orbit has changed are collected by a chemical collecting section disposed below and prevented from being supplied to the substrate.
In the method of U.S. patent application Ser. No. 09/335,508, the gas generating film is heated and gasified by light irradiation, whereas the influence of light irradiation upon chemicals dropped ahead of the film should be controlled. However, the method of the U.S. Patent Application does not take any measures against the influence of light irradiation.
If, moreover, a plate-like gas generating film is placed in a unit moving section, the number of times the chemicals drop can be reduced only about 100 times because the dropped chemicals are restricted by the size of the film. In order to cut off the supply of chemicals to the entire surface of a substrate to be processed, the chemicals have to reduce from 105 to 107 spots of the substrate. It is therefore the problem of the U.S. Patent Application that the number of spots from which the chemicals are reduced is small.
An object of the present invention is to provide a deposition apparatus for forming a film by locally controlling the number of chemicals to be dropped by the pressure of gas generated from a gas generating film by irradiation of light, which is capable of controlling the influence of light applied to the gas generating film upon the chemicals.
Another object of the present invention is to provide a deposition apparatus capable of easing the restriction on the number of times the chemicals to be dropped are reduced.
In order to attain the above objects, the present invention is constituted as follows.
(a) A deposition apparatus comprising: a chemical discharging nozzle for continuously discharging chemicals to a substrate to be processed; a gas spraying section arranged below the chemical discharging nozzle, for spraying gas on the chemicals discharged from the chemical discharging nozzle and changing an orbit of the chemicals by pressure of the gas; a chemical collecting section for collecting the chemicals the orbit of which is changed by the gas spraying section, the chemical collecting section being arranged so as to interpose the chemicals between the gas spraying section and the chemical collecting section; and moving means for moving the chemical discharging nozzle and the substrate relatively with each other, wherein the gas spraying section includes: a laser oscillator for emitting a pulse laser beam; and a gas generating film that generates the gas when heated and gasified by the laser beam emitted from the laser oscillator.
(b) A deposition apparatus comprising: a chemical discharging nozzle for continuously discharging chemicals to a substrate to be processed; a gas spraying section arranged below the chemical discharging nozzle, for spraying gas on the chemicals discharged from the chemical discharging nozzle and changing an orbit of the chemicals by pressure of the gas; a chemical collecting section for collecting the chemicals the orbit of which is changed by the gas spraying section, the chemical collecting section being arranged so as to interpose the chemicals between the gas spraying section and the chemical collecting section; and moving means for moving the chemical discharging nozzle and the substrate relatively with each other, wherein the gas spraying section includes: a light emitting section for emitting light; a tape-shaped gas generating film that generates the gas when heated and gasified by the light emitted from the light emitting section; and a winding device for winding the gas generating film.
The above constitution of the present invention produces the following advantages:
By controlling the pulse width of a laser beam so as to stop the irradiation of the laser beam before the gas generating film is gasified, the laser beam can be prevented from being applied to the chemicals to be dropped. Therefore, the laser beam does not have an influence on the chemicals.
Since the winding device winds the tape-shaped gas generating film, the restriction on the number of times the chemicals to be dropped are reduced can be eased.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.